Optimum Number of Measurements To Be Made In Kinematic Calibration

M.Á. Pérez Rueda, A. Lara Feria, M. Merino Llorente, A. Calvo Fernández (Spain)


Identification, optimization, simulation, robot calibration, quaternion.


An important step in a model-based robot calibration process is the identification of the manipulator’s unknown kinematic model parameters from end-effector pose measurements and robot joint position readings at known measurement configurations. Kinematic identification is the process by which all kinematic model parameters of a robot manipulator are identified given a set of end effector pose measurements and the corresponding joint position measurements. The need for robot calibration arises in many applications that necessitate off-line programming and situations that require multiple robots to share the same application software. This work proposes a new approach for the calibration of robots based on quaternion vector pairs. In this paper, an alternative approach to the homogeneous matrices, employing the quaternion-vector pair is proposed. A quaternion contains four parameters, and they have been proved to be a minimal set for defining a nonsingular mapping between the parameters and their corresponding rotational transformation. The following issues are investigated: number of measurements required for the algorithm to converge, and accuracy performance of the proposed algorithm under different levels of noise intensity. Experimental results obtained in the calibration of an industrial manipulator are presented.

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